With the introduction of RN (Relay Node), there are three wireless links of mobile communication system comprising Relay: the direct link between eNB (evolved NodeB) and macro UE (macro User Equipment), the backhaul link between eNB and RN, and the access link between RN and R-UE (the user equipment served by RN). Considering the wireless communication signal interference, the three links need to use orthogonal wireless resources. In the same band, in order to avoid self-interference, relay node cannot transmit and receive data simultaneously. In the LTE-A (Long Term Evolution-Advanced), relay node can exchange backhaul data with its donor eNB using MBSFN (Multicast Broadcast Single Frequency Network) sub-frames, as shown in FIG. 1.
In more detail, as shown in FIG. 2, in one MBSFN sub-frame, a relay node transmits PDCCH (physical downlink control channel) to the user equipment (R-UE) served by the relay node on one or two OFDM (Orthogonal Frequency Division Multiplexing) symbols. On the other OFDM symbols of this MBSFN sub-frame, the relay node can receive control information (R-PDCCH) and data information (R-PDSCH, Physical Downlink Shared Channel) from the donor eNB. In the frequency domain, R-PDCCH can be transmitted on a set of pre-configured resource blocks. Different relay nodes can share these R-PDCCH resource blocks, and each relay node blindly detects its DL grant and UL grant in this set of resource blocks. An example is shown in FIG. 2 where RN1 and RN2 share the same set of R-PDCCH resource blocks. Relay node derives its R-PDSCH resource allocation according to the DL grant blindly detected from the set of R-PDCCH resource blocks. Base station can schedule macro UE and relay node in one sub-frame, as long as the allocated resources are orthogonal for the macro UE and relay node. The downlink data of Macro-UE is called PDSCH, as shown in FIG. 2.
While the set of R-PDCCH resource blocks can be shared by multiple relay nodes as shown in FIG. 2, the set of R-PDCCH resource blocks can also be specific to one relay node (RN specific), as shown in FIG. 3, where the R-PDCCH resource blocks of RN1 is specific to RN1, i.e. each resource block used to transmit R-PDCCH of RN1 only comprises the R-PDCCH of RN1. The control signaling for RN1 transmitted in RN1's R-PDCCH resource blocks comprises DL grant and UL grant etc. Others R-PDCCH resources can exist, and may be shared by several relay nodes, for example, by RN2 and RN3.
However, there is no detailed design of relay node dedicated R-PDCCH, thus not able to satisfy the need to have relay node dedicated R-PDCCH.